<?php // $Id$ /** * Return data from the persistent cache. * * @param $key * The cache ID of the data to retrieve. */ function cache_get($key) { global $user; // Garbage collection necessary when enforcing a minimum cache lifetime $cache_flush = variable_get('cache_flush', 0); if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) { // Time to flush old cache data db_query("DELETE FROM {cache} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush); variable_set('cache_flush', 0); } $cache = db_fetch_object(db_query("SELECT data, created, headers, expire FROM {cache} WHERE cid = '%s'", $key)); if (isset($cache->data)) { // If the data is permanent or we're not enforcing a minimum cache lifetime // always return the cached data. if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) { $cache->data = db_decode_blob($cache->data); } // If enforcing a minimum cache lifetime, validate that the data is // currently valid for this user before we return it by making sure the // cache entry was created before the timestamp in the current session's // cache timer. The cache variable is loaded into the $user object by // sess_read() in session.inc. else { if ($user->cache > $cache->created) { // This cache data is too old and thus not valid for us, ignore it. return 0; } else { $cache->data = db_decode_blob($cache->data); } } return $cache; } return 0; } /** * Store data in the persistent cache. * * @param $cid * The cache ID of the data to store. * @param $data * The data to store in the cache. Complex data types must be serialized first. * @param $expire * One of the following values: * - CACHE_PERMANENT: Indicates that the item should never be removed unless * explicitly told to using cache_clear_all() with a cache ID. * - CACHE_TEMPORARY: Indicates that the item should be removed at the next * general cache wipe. * - A Unix timestamp: Indicates that the item should be kept at least until * the given time, after which it behaves like CACHE_TEMPORARY. * @param $headers * A string containing HTTP header information for cached pages. */ function cache_set($cid, $data, $expire = CACHE_PERMANENT, $headers = NULL) { db_lock_table('cache'); db_query("UPDATE {cache} SET data = %b, created = %d, expire = %d, headers = '%s' WHERE cid = '%s'", $data, time(), $expire, $headers, $cid); if (!db_affected_rows()) { @db_query("INSERT INTO {cache} (cid, data, created, expire, headers) VALUES ('%s', %b, %d, %d, '%s')", $cid, $data, time(), $expire, $headers); } db_unlock_tables(); } /** * Expire data from the cache. * * @param $cid * If set, the cache ID to delete. Otherwise, all cache entries that can * expire are deleted. * * @param $wildcard * If set to TRUE, the $cid is treated as a substring to match rather than a * complete ID. */ function cache_clear_all($cid = NULL, $wildcard = FALSE) { global $user; if (empty($cid)) { if (variable_get('cache_lifetime', 0)) { // We store the time in the current user's $user->cache variable which // will be saved into the sessions table by sess_write(). We then // simulate that the cache was flushed for this user by not returning // cached data that was cached before the timestamp. $user->cache = time(); $cache_flush = variable_get('cache_flush', 0); if ($cache_flush == 0) { // This is the first request to clear the cache, start a timer. variable_set('cache_flush', time()); } else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) { // Clear the cache for everyone, cache_flush_delay seconds have // passed since the first request to clear the cache. db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); variable_set('cache_flush', 0); } } else { // No minimum cache lifetime, flush all temporary cache entries now. db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); } } else { if ($wildcard) { db_query("DELETE FROM {cache} WHERE cid LIKE '%%%s%%'", $cid); } else { db_query("DELETE FROM {cache} WHERE cid = '%s'", $cid); } } }